OLYMPUS Digital SLR Camera FOUR THIRDS
Four Thirds System
Designed completely for digital applications.  Building a digital-specific system Designed completely for digital applications.  Building a digital-specific system
OLYMPUS developed every part of its digital interchangeable lens-system SLR camera for digital applications. Using the new Four Thirds System, this is a totally new digital SLR camera system, based on a new design and development concept taking full advantage of the native strengths of the digital camera. The Four Thirds System breaks completely from today's 35mm SLR camera lens systems. Employing a new interchangeable lens developed specifically for digital cameras, the system is based on an optical design suited to the characteristics of digital cameras. The aim of this new system is to provide lens optics that deliver superb image quality, by harnessing the full potential of the image sensor, in a compact package offering superb handling and mobility. OLYMPUS is helping to create a new culture of digital photography, by offering a new digital SLR camera system suited to the digital era.
Image sensor size
In general, current digital SLR cameras with interchangeable lenses are based on the lens systems of conventional 35mm SLR cameras. As a result, they must be equipped with large image sensors, comparable in size to those used for 35mm and APS film. However, because the imaging characteristics of these large CCDs are fundamentally different from those of film, a number of issues can prevent them from achieving their full performance potential. These include: (1) Although film is capable of responding to light striking the surface at a high angle of incidence, a high angle of incidence can prevent sufficient light from reaching sensor elements at the periphery of a CCD and result in reduced color definition, particularly when shooting with wide-angle lenses. (2) To achieve the resolutions required by the micron pitch of today's CCDs, the demands of optical design tend to result in the use of larger and heavier lenses.

We explored the ideal balance of image quality, size, and system scalability in great detail, and arrived at the 4/3-type image sensor size as the ideal combination. By using a lens designed specifically for digital cameras based on the 4/3 size, we were able to deliver image quality and mobility surpassing anything available to date.
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Standardized lens mounts
Each manufacturer of 35mm SLR camera systems uses its own unique mount and other specifications, which are inherited by today's digital SLR cameras. The Four Thirds System is a totally new digital SLR camera system. It delivers superb image quality and mobility, while also giving consideration for standardization, in order to make things more convenient for the user.

In September 2002, OLYMPUS CORPORATION and US-based Eastman Kodak announced their agreement to adopt the Four Thirds System, and established the Universal Digital Interchangeable Lens System Forum in order to popularize the new system. The forum is actively recruiting manufacturers to adopt the Four Thirds System. This new standard has been accepted by major companies including Fuji Photo Film, Sanyo Electric, Sigma, Matsushita Electric and Leica Camera AG.
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